I received advise to change the oil pump as a preventative maintenance (have 140,000 mls; not sure if original) since it is prone to fail.
If it goes bad, does it go suddenly and cause damage, or gradually (what are the signs?)
If change is advised: anyone have a good one for sale?

 

The only failures I've heard of are people not using seafoam to control the sludge, which can clog the oil pump pickup tube's filter screen and end up starving the engine and blowing it. Maybe someone else can chime in with contrary info but I've never heard of an oil pump change as preventative maintenance...